Huh, what do you know...
I learned of the Douglas Aircraft inspiration several years ago (through Nyrath's fascinating site), but I never stopped to consider the production managed to obtain and modify existing miniatures originally built for a tradeshow. But thinking about it, that makes a LOT of sense given how frugal the series was. Even Gerrold tried to think fiscally by suggesting the production could place "set dressing" upon the soundstage exteriors to appear as grain warehouses. Looking back, I just can't imagine the show going to the expense of building a space station miniature "from scratch" that might only appear in that one episode (though the footage shot was reused in "The Ultimate Computer").
Tangently related, since the redressed Douglas pods had "nested clamshell" panels, how did they get confused with elevated "ribs" that found their way onto the AMT kit? Did NO images of the station model exist beyond the grainy final generation optical as it appeared on screen? There exist photos of the 11 foot hero model against a blue screen. Same for the Botany Bay. There's even a couple of shots of Chang's Romulan warbird suspended upon its wires. But nothing "behind the scenes" exists of the K-7?